1. Field of the Invention
The present invention relates to the field of drilling apparatus, and more particularly to a novel device for drilling a square hole which employs a twist drill and a chisel simultaneously to form the square hole.
2. Brief Description of the Prior Art
In the past, it has been difficult to drill or form a square hole due to the fact that the use of a twist drill readily removes bulk material from the work piece but results in a round hole. However, when a chisel having square ends is employed, a square hole can be made but the removal of bulk material requires time and is relatively inefficient. Some attempts have been made to overcome these problems by employing a square chisel with a twist drill in the center so that bulk material is removed by the twist drill and the square corners of the hole are made by the square chisel. Although this procedure and apparatus does work for its intended purpose, difficulties have been encountered when mounting and holding such a drill and chisel combination so that the drilling procedure is efficient and can be performed at a rapid pace.
Therefore, a long-standing need has existed to provide a device or apparatus which will readily adapt a combined chisel and twist drill into a single unitary construction for mounting on the rotating shaft of a conventional drill press. Such a device is preferred to permit rotation of the twist drill and stationary mounting of the square chisel whereby both elements operate in unison to remove work piece material and shape the hole simultaneously.